Wireless communication systems are widely used to provide voice and data services for multiple users using a variety of access terminals such as cellular telephones, laptop computers and various multimedia devices. Such communication systems can encompass local area networks, such as IEEE 802.11 networks, cellular telephone and/or mobile broadband networks. The communication systems can use one or more multiple access techniques, such as Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA), Code Division Multiple Access (CDMA), Orthogonal Frequency Division Multiple Access (OFDMA), Single Carrier Frequency Division Multiple Access (SC-FDMA) and others. Mobile broadband networks can conform to a number of system types or partnerships such as, General Packet Radio Service (GPRS), 3rd-Generation standards (3G), Worldwide Interoperability for Microwave Access (WiMAX), Universal Mobile Telecommunications System (UMTS), the 3rd Generation Partnership Project (3GPP) including Long Term Evolution (LTE), IEEE 802.11 networks, and Evolution-Data Optimized (EV-DO).
In the downlink channel (DL) of a wireless communication system, coordinated multipoint (CoMP) transmission schemes are used to enhance coverage. By using multiple transmitters in a system, and choosing among the multiple transmitters or jointly broadcasting among the multiple transmitters, coverage can be expanded and data rates can be increased over systems that relay on a single transmitter. In order to implement CoMP schemes, however, user devices or user equipment (UE) typically need to provide more feedback to the base station. Different CoMP schemes are suitable for different deployment scenarios, and, therefore, generally have different feedback requirements.
Supporting these different feedback schemes can come at a cost of extra system overhead. For example, channel feedback can be used to support CoMP transmission, but generally requires a very high feedback overhead. Furthermore, multiple implicit feedback schemes for different DL CoMP transmission schemes can be used, but generally require multiple feedback formats, which, in turn, require more system resources to implement. In multiple feedback schemes, the transmission mode and feedback should follow each other, and there is a lack of flexibility at the scheduler. Multiple feedback schemes also generally would need multiple feedback mechanisms and channels in the standard, with different optimization criteria.